The applicant proposes first to evaluate the efficacy of a mutant form of the HIV receptor in blocking replication of HIV-1. This receptor, designated sCD4-KDEL, contains a specific retention signal for the endoplasmic reticulum and blocks transport of the HIV-1 envelope glycoprotein from the ER to the cell surface. Expression of this molecule at high levels in T-cells is likely to suppress assembly of infectious HIV-1. Ultimately, expression of this molecule might be useful in a procedure of intracellular immunization designed to prevent HIV maturation in a patient's T-cells. The second series of experiments proposed are closely related to the first. Here they would like to generate other mutant forms of CD4 containing specific signals that target the HIV glycoprotein for degradation in lysosomes or in the endoplasmic reticulum. Their third goal is to determine the effect of the HIV glycoprotein on the tyrosine protein kinase p561ck which is bound to the cytoplasmic domain of CD4 in T-cells. They are particularly interested in determining the effects on kinase activity and on the substrates phosphorylated. Because intracellular tyrosine protein kinases have been implicated in regulation of cell growth, regulation of p561ck could be relevant to the pathology of AIDS. The fourth goal is to develop a system in which the HIV-1 glycoprotein can be incorporated into the VSV particles in the absence of any HIV. These experiments will employ a virus rescue system recently developed in the laboratory. If infectious VSV particles containing altered gp12O/41 can be generated, they would have an immediate use in rapid tests for HIV neutralizing antibody which would not require growth of HIV. These pseudotypes would be safe to work with as they could not contain any HIV or HIV(VSV) pseudotypes and might prove useful as a vaccine if produced on a large scale.